Bi-Epitaxial Template Grain Boundary Weak Links on MgO: High Tc Josephson Junctions
Using pulsed laser deposition, bilayers of YBa2Cu3O7ICeO2 and single layers of YBa2Cu3O, have been deposited on (001) oriented MgO substrates. The orientation of CeO2 and the superconducting properties of YBa2Cu3O7 have been investigated as a function of the deposition temperature and the distance between target and substrate. These results have been used to fabricate bi-epitaxial template grain boundaries in which the template layer has been structured using the CaO lift-off technique. The YBa2Cu3O7 top layer has been structured into Josephson junctions. The junctions showed RSJ-like IV curves at low temperatures. At higher temperatures the IV curves were much more rounded. For temperatures just below the critical temperature of the superconductor a resistive tail was observed in the R(T) measurements. The tail could be fitted with the Thermally Activated Phase Slippage theory. The results are in good agreement with the fits of the Ic(T) curves.
KeywordsCritical Temperature Deposition Temperature Josephson Junction Substrate Distance Normal Resistance
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